Method and batch or mixture for making illuminating-glass.



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UNITED STATES PATENT ouuron.

enema A. naesnrn, or PfTTsBuR'GH, PENNSYLVANIA, fasszeuoa To MAC'BETH- EVANS GLASS COMPANY, or PITTSBURGH, PENNSYLVANIA, A CORPORATION OF PENNSYLVANM.

names AND BATCH R MIXTURE For. Maxine ILL'uMINATINo-GLAss.

an; nrdwn To all whom it may concern Be it known that I, GEORGE A. MACBETH, a citizen of the United States, residing at Pittsburgh, in the county of Allegheny and State of Pennsylvania, have invented a certain'new and useful Method and Batch or Mixture for Making Illuminating-Glass, of which the following is a specification.

The invention relates to a method and batch or mixture for making glass for illuminating purposes such as in electric and other shades and globes. It has for its primary objects, the provision of a process and batch which will produces snowwhite glass which is not clear but which is translucent to a high degree and will transmit light without the reddish or yellow color known as fire, the glass in these respects distinguish ing from the well known opal glasses which are either substantially opaque (and known as milk glass) or are to some degree translucent, in which case the coloring above referred to as fire is always noticed when light is observed through the glass; the provision of a process and batch which will produce a 7 glass which transmits light better than the opal glasses and which is subject to a minimum amount of breakage upon the application of heat, and the provision of a batch and process which will produce a glass having a white luminous appearance when transmitting light, with such light diifused in a pleasing manner restful to the eyes, and with a minimum loss of illuminating power.

In carrying out my invention I first take a batch or mixture somewhat similar to a batch or mixture used in the manufacture of colorless clear glass, the preferred ingredients whereof will be hereinafter more partic ularly pointed out, and to such basic batch or mixture I add substances, one of which is preferably oxid of aluminum and the other a fiuorid, preferably fluorspar, although some other fluorid might be used. The use of the oxid of aluminum with this fiuorid apparently produces throughout the glass minute specks, the larger of which are ordi-' narily visible to the naked eye, and which have the effect of diffusing or scattering the light and giving the glass its white luminous appearance. The specks in the finished ware are elongated in shape, and I believe them to be bubbles of silicon fiuorid gas held in sus- Specification of Letters Patent.

Application 'flled May 9, 1913. Serial No. 766,561.

glass.

Patented May 19, 19 14.

pens-ipn in the material and elongated during pressing or blowing the glass into molds.

n manipulating the glass batch, the duration of operation and the degree of heat must be regulated so as not to entirely ob literate the so-called specks or bubbles, which obliteration appears to result when the heating is too intense or is carried on for too long aperiod. I therefore stop the heatmg operation at a time short of the product on of complete transparency and the obhteratio'n of the specks or bubbles from the glass, the glass tending to return to its colorless crystal stage if the operation is continued too long. In carrying out the operation I have found that good results are obtained in a furnace working at a temperature of approximately 2700 degrees F., although this may be varied, and changes in temperature (as between 2500 degrees and 3000 degrees may be compensated for, in a measure at least, by variations in the mixture or the length of time of the "operation, which latter in many cases I have found to be less than twenty four hours.

The specific combination of ingredients in the foundation or basic mixture or batch which I have found to give the best results is as follows: I

Sand 100 lbs. Lead oxid i 155 lbs. Soda s 21% lbs. Niter 5% lbs. Salt 5;; lbs. Borax 1;} to 211 lbs.

To the foregoing batch are added 18.12 pounds of hydrate of aluminum (AI H O containing about 11.84 pounds of oxid of alumina (A1 0 and six pounds of fiuorspar (Call The materials are mixed together and fused as-heretofore indicated.

The proportions of the oxid of alumina and the fluoridare not absolutely fixed, but may vary somewhat. The limit in the ratio of the fluorid to the oxid' of alumina is reached when the resultant glass becomes an opal glass instead of a translucent glass without the fire characteristics of the opal The relative proportions will also vary somewhat, depending upon the variations in the basic or foundation glass.

- The glass produced by the present process is from other glasses containing fiuorin, by the fact that the glass of the present process is translucent and yet without'the characteristic known as fire of opal, whereasthe fiuorid glasses as heretofore produced were all properly definable as milk or opal'glasses, being either white and opaque, or else partially opaque and showing with transmitted light a reddish or yellow color known to the trade as fire and bearing a resemblance to the color in natural op'als.

What I claim is v l. The herein-described method of manufacturing illuminating glass, which consists in fusing together a foundation mixture ca-' pable of making substantially colorless clear glass with an aluminum oxid compoimd, and a fiuorid, the quantity of the aluminum oxid compound by weight being greater than that of the fiuorid, and the amount of aluminum by weight contained in the aluminum oxid compound being greater than that of the fiuorin contained inthe fiuorid, and the heating operation being stopped before the glass returns to a clear glass stage and before the specks are eliminated.

2. The herein described method of manufacturing illuminating glass, which consists in. fusing together a foundation mixture capable of making substantiall colorless clear glass and including a chlorld, with an aluminum compound and a fluorin com-' pound, the quantity by weight of the aluminum contained in the aluminum compound being greater than that of the fiuorin contained in the fluorin compound, and the heating operation being stopped before the glass returns to a clear glass stage "and before the specks are eliminated.

3. The herein described mixture for manufacturing illuminating glass, which consists in a foundation mixture capable of making substantially colorless clear glass, oxid of aluminum and a fiuorid, in the following quantities by weight-450 parts of the foundationrmixture, ,9'to 15 parts of oxid of aluminum; and 3 to 8 parts of the fluorid.

4. The herein described mixture for manufacturin illuminating glass, which consists .111 a'batc containing 150 parts by weight ing substantially colorless clear glass, a compound containing aluminum and a compound containing fiuorin, the quantity of the aluminum in the batch'by weight being from 4 to 8 parts, and the quantity of fluorin in the batch by weight ranging from 2 to 4:

arts. p 5. The herein described mixture for manufacturing illuminating glass, which consists in a foundation mixture capable of making substantially colorless clear glass and including chlorid, an aluminum compound, and a fiuo'rin compound the amount of aluminum by weight contained in the aluminum compound being greater than that of the fluorin contained in the fluorin compound, and the mixture.

6. The herein described mixture for manufacturing illuminating glass, which consists in afoundation mixture capable of making substantially colorless clear glass, an aluminum compound and a fluorin compound, the amount of fluorin by weight contained in the weight of the aluminum and fluorin c0m-- bined being at least 1% of that of the entire of the foundation mixture capable of makfluorin compound being less than 11% of that of the aluminum contalned in the aluminum compound; and the weight of aluminum and fluorin compound com ined belng at least 7 z The herein described mixture for manufacturing illuminating glass, which consists v GEQRGE A. MACBETH.

Witnesses ARoHwoR'rH MARTIN, Ln'rrm A. Mxnns.

-1% of that of the entire mixture. 

